A conventional delimber of the general type this invention is concerned with is illustrated in Hamby, Jr. U.S. Pat. No. 4,899,794. There it will be seen that a cutter head assembly is mounted in a support yoke for pivotal movement about a horizontal axis relative to the yoke. The yoke includes a floor plate which is mounted for rotational movement about a vertical axis on a horizontal base frame. The yoke floor plate is supported for this rotation on an annular bearing adjacent the front end of the delimber. Adjacent the rear end of the delimber a pair of support rollers fastened to the bottom of the yoke floor plate ride on the roof plate of the base frame in an arc to support the yoke and cutter head assembly as they rotate during delimber operation.
With delimbers of this type, it is conventional to provide some kind of vertical adjustment capability for the aforedescribed base rollers. Current technology is to mount rollers on the base frame rather than the yoke floor plate, as is shown in the Hamby, Jr. '794 patent delimber. This current technology involves base rollers that are vertically adjustable to assure positive contact with the bottom surface of the yoke floor plate. Adjustment is conventionally effected through the use of four vertical bolts, one on either side of each of two rollers. The bolts are fixed in place by jam nuts which are tightened against the roller housing. These bolts must be accessed from underneath the delimber base frame, and are threaded upward to raise a roller and downward to lower the roller. Careful attention must be given to adjusting each of the bolts equally to ensure parallel contact between the roller and the bottom surface of the yoke floor plate because operation of the delimber with one side of a roller higher than the other will result in uneven wear of the roller, roller bushings, and the mating yoke floor plate surface.
Adjustment is also made difficult because access to the bottom of the base frame is commonly obstructed due to cut limbs and other debris that build up around the delimber on the job site. Furthermore, knowing when individual roller height has been properly adjusted is also a problem because the area of contact between the yoke floor plate and a roller is not readily visible to the operator.